@Fozz:
We often discuss two or three things at the same time. For Go North East, the bulk of our posts lately have been in relation to the upcoming service changes. However, we've had a few other minor topics amidst this discussion (ie accidents, loans, application of vinyls, etc).

So we'd have a 'January 2015 Changes' thread, but also a thread for 'Application of Vinyls', etc. If you had no interest in the discussion about vinyls, you could skip over this and only read the January 2015 changes thread, marking the vinyls thread as read. After the service changes are implemented, we may discuss the changes for a few days more with any photos or suchlike, but after a set amount of time with no posts in the thread, we could lock it and put it into an 'archive' sort of sub-forum, where it could still be referred to, but nobody could post in it. Obviously if there was a need for the thread to be unlocked after that period of time, a moderator could easily do this.